You are trying to access a memory address via a pointer whose value is NULL. For example:

"int * aPointer;
aPointer = NULL;
int anInteger;
anInteger = *aPointer"

The above will fail on the last line with KERN EXEC 3.

Other piece of code that has the same problem is:

"class C {
public:
    int *iInteger;
}; // C

....

C *myClass = NULL;

int anInteger;

anInteger = myClass->iInteger;"

This will also fail on the last line, since "myClass" has the value "NULL".

However, these mistakes are easily caught using a debugger. Do you have one to use?